Questions tagged [linux]

A free and open source POSIX compatible operating system with a monolithic kernel and a kernel module system. Originally created by Linus Torvalds.

Filter by
Sorted by
Tagged with
2
votes
3answers
6k views

Where can I get Linux malware samples?

There have been numerous sites stated in this wonderful post that one could retrieve malware samples. However, I am having a difficult time (sorry D:) locating Linux-specific malware from those sites ...
2
votes
3answers
1k views

Good Binary Vulnerability Research Resources [closed]

I have spent the past several months refreshing my knowledge of x86 and updating to understand x64, and going through binary exploit development courses. Now that I am equipped with the necessary ...
2
votes
1answer
4k views

What does fs and gs registers provide in Linux?

In a 64 bit ELF binary I found it mainly uses fs register to get some values. How can I know which value it wants to access? I'm familiar with that NT kernel uses fs and gs register for TEB structure ...
2
votes
2answers
710 views

Find sigtrap function

I'm reversing a program that uses a lot of BREAK/int 3 (Linux). I guess that the code contains something like: void sigtrap_func(int sig) { (some stuff..) } int main() { signal(SIGTRAP, ...
2
votes
2answers
6k views

How can I change the value of a variable while debugging?

I know that I can output the value of a variable using (gdb) p var_name $1 = "varvalue" Is there a way to set the value of a variable while debugging with gdb? The document that I'm using doesn't ...
2
votes
1answer
155 views

Unknown archive format from QNX operating system

We are reverse engineering a QNX system and we have found a small file that is uploaded to the system. It appears to be either a file system image or an uncompressed archive of some sort. We can't ...
2
votes
1answer
469 views

possible to rebase an ELF file?

Is there any way to rebase an ELF file? (i want to load an elf binary at 0x40000000, not at 0x08040000 which is typical base) I found this tool(prelink, http://en.wikipedia.org/wiki/Prelink), but it'...
2
votes
2answers
148 views

ASLR in Linux Vs Windows

I am quite new in binary exploitation. I am doing a lot of beginners exercise here. I am confused about ASLR. I tried some binary exploitation thing in Linux. It was recommended that I should stop ...
2
votes
2answers
301 views

Prevent Memory Inspection in a Cython program?

Cython is a great way to protect the source code of a Python program. However, memory inspection and memory reverse engineering can still be done to this Cython program. What are ways to prevent (or ...
2
votes
1answer
57 views

Correct my understanding on a basic allocation memory

Here is the function If I understand correctly: There is a buffer of size 256 bytes created (malloc) in this buffer, the first 32 bits are set to 0 (because dword designates 32bits size) the next 32 ...
2
votes
1answer
35 views

Comparing the static address of the vtable of a class, to the pointer to it held by the object

I know this is compiler/ABI dependent, not necessarily standardized, etc. I've always assumed, from what I've read in several places (e.g. an answer here or the example in wikipedia), that a typical ...
2
votes
1answer
351 views

ildasm on Linux: “original” ildasm.exe same as dotnet-ildasm?

I would like to use ildasm on Linux. The original one, that comes with the .NET SDK and can be found on Windows e.g. at c:\Program Files (x86)\Microsoft SDKs\Windows\v8.0A\bin\NETFX 4.0 Tools\. I ...
2
votes
1answer
451 views

Reverse getline(cin, text)

I'm trying to solve a crackme that was made in C++, and I was able to "recreate" a function call, through the library calls the program made. Here's the piece of code that I'm trying to reverse: ...
2
votes
1answer
101 views

Process Immediately Killed

I'm trying to reverse an ARM executable. It's for an embedded system, but I don't have any details about the normally targeted environment. Here's what file shows: ELF 32-bit LSB executable, ARM, ...
2
votes
2answers
703 views

Step Over not working in GDB

In the function below, let's say EIP is 0x400688. Now, I want to step over the call instead of stepping inside the subroutine. 0x40067a <main+4> sub $0x20,%rsp ...
2
votes
1answer
904 views

Radare2 webui - need help setting it up

How can you set up Radare2 webui in Kali or Ubuntu or any other OS? I've tried so many different methods but none of them have worked so far. I think both of them are debian based so that might be ...
2
votes
1answer
140 views

Determining an application's library call behaviour

I have a closed source Linux library libfoo that makes calls into another closed source library libbar for additional (mostly unneeded) features. However, I can't use libbar for ethical reasons, so I ...
2
votes
1answer
683 views

Custom gdb output

Yesterday i noticed a nice output from dbg while going through a write up on the internet. As am new to dbg i googled a lot as i wanted to make dbg work similar for me. As seen below this ...
2
votes
2answers
237 views

Where to get started with reverse engineering a usb video device on Windows?

I have a piece of proprietary hardware that I'm trying to reverse engineer and write a cross-platform open-source driver for. This device has an IR camera on it, and it seems to be using the UVC ...
2
votes
1answer
293 views

hooking libhoudini on x86 emulator

I'm trying to hook libhoudini to debug an application instruction by instruction using frida but frida not supports it i need a example on how can this be achieved! I'm using a x86 emulator to run arm ...
2
votes
1answer
204 views

reverse engineering hi3516ev200

I am new to reverse engineering and will describe my situation thus far. In short, I am looking for some tips on what to do next to gain access to a piece of hardware I am playing with. I bought a ...
2
votes
1answer
872 views

Unexpected SEGFAULT when there's apparently nothing that would cause it

This is a from a CTF problem I'm working on. Hopefully it's appropriate to ask this question here. Above is the GDB output when the segfault goes off. movaps is the offending instruction, meaning ...
2
votes
1answer
697 views

Help needed to extract u-boot kernel & rootfs - nxp lpc 3143 processor

I have a board where in principle aim at emulating a DVD-ROM loading iso file from a drive. This board is running a ARM CPU with 32MB of ram and has no vga output. The firmware update comes with 2 ...
2
votes
2answers
576 views

mprotect syscall not working

I want to modify the protection of the .text segment to RWX using a shellcode. In the shellcode, I can issue the syscall for mprotect however it's not working. Per the sys_mprotect definition, it ...
2
votes
1answer
2k views

extract zImage from MS-DOS executable

I have an aarch64 kernel image with the following magic number: root@localhost:/# cat msImage|xxd -l4 00000000: 4d5a 0091 MZ.. root@localhost:/# file msImage ...
2
votes
1answer
1k views

How can I view the dynamic symbol table of a running process?

For any dynamic executable on Linux there is a dynamic linker that stores the current symbol bindings somewhere. So when a new library is loaded it knows whether to bind the symbol or not. For ...
2
votes
2answers
3k views

Changing Entrypoint in ELF executable

I wrote some code that does the following: Searches for and finds an offset in a binary file to add code (looks for a sequence of 00s I can overwrite). Then, I change the entrypoint of the ELF to ...
2
votes
2answers
3k views

Static analysis of Windows executable from a Linux platform

I am trying to do some static analysis on crackmes written for Windows on a Linux platform. I am using radare2. My problem is that most of the time I am unable to find the "real" code, for example the ...
2
votes
2answers
543 views

Putting an application in between client and server

I'm attempting to reverse engineer (without dissecting the source code, as my understanding is that reverse engineering by analyzing input and output and building something from scratch that fits is ...
2
votes
1answer
479 views

File Type - VCDIFF binary extract

I have a file I am trying to extract to view and I'm stuck... If I use binwalk I am able to get the gunzip file but unable to extract it... If I attempt to extract with gunzip I return the errors and ...
2
votes
1answer
2k views

gdb setting fs register on Linux

I'm debugging an ELF 64-bit binary using gdb and I notice that the %fs register is set to 0x63. For some testing that I'd like to perform I'd like to set the %fs register to 0x00. I tried doing a set ...
2
votes
1answer
622 views

Are there ANY supported Fermi Disassemblers out there?

I've recently started exploring the world of GPU-based malware. Academia doesn't have a ton of papers here, but there's some powerful ones. I'm looking at trying to improve the communities tools in ...
2
votes
1answer
148 views

Linux keyboard driver windows reverse engineering

I have toshiba portege x30-f laptop with Fn keys not working under linux. I've read some articles about usb drivers reverse engineering, but the keyboard connected not via usb. As I can understand it ...
2
votes
2answers
108 views

Newbie problems exploiting a format string vulnerability

I encountered a print format vulnerability challenge in a CTF. I don't know anything about these vulnerabilities, so I'm working my way through Saif El-Sherei's format string exploitation tutorial ...
2
votes
4answers
762 views

Endoscope Camera YPC99 - how to stream on linux

I'm trying to stream video from endoscope camera YPC99 on linux PC using the WiFi connection. From what I have found so far the camera is using IP 192.168.1.1. It supports RTSP protocol on port 7070 (...
2
votes
2answers
564 views

Repacking an embedded initramfs

I'd like to modify some of the init scripts in an initramfs that is embedded in a kernel bzImage. I know I can modify them by not changing the size of any files (e.g. by commenting out lines, and ...
2
votes
1answer
499 views

`qemu-mips-static` chroot causing `Invalid ELF image` error

I'm trying to emulate a MIPS binary on my Ubuntu 16.04 x86 system, but I'm not able to. I chroot into the squashfs-root filesystem that I got from binwalking the firmware image. kan3k1@kaido:~/...
2
votes
1answer
136 views

ARM system crashes after changing stack address

-- Edit with latest update on the problem, it is not solved yet :( -- While playing with an ARM embedded Linux system (Version 3.8.13), out of curiosity, I created a small "debug" kernel module. ...
2
votes
1answer
2k views

Disassemblers resolving (ELF) section names

I'm working with linux executables and was just wondering how it is that section names are resolved to addresses upon disassembly of an ELF. For example take some random disassembly output from ...
2
votes
1answer
3k views

IDA Pro debugging: follow child process

I'm reverse engineering a malware that creates a number of child processes and I'm trying to do dynamic analysis of the ELF binary with IDA Pro and IDA's Local Linux Debugger, but I can't get IDA to ...
2
votes
1answer
596 views

How to store files on a router's NAND without writing the whole firmware

I want to modify my ZyXEL P-2812HNU-F1 dsl router by storing some extra files in /etc. However, /etc is mounted as tmpfs so changes are lost on reboot. But there's probably a way around it ;) # cat /...
2
votes
1answer
627 views

Writing own custome syscall/int 0x80 on x64 system

Is there a way to write my own syscall/int 0x80 without using them? So, normally it goes like setup registers ... syscall or int 0x80 and I am interested in doing this without syscall/int 0x80 ...
2
votes
1answer
330 views

Mechanisms to stop serial console accepting input on a Linux system?

I am working on a simple embedded system based around an Olinuxino board. This has a serial console header onboard. TX and RX are both connected to the respective pins on the microcontroller (i.e. ...
2
votes
1answer
270 views

How can I figure where my router stores it's configuration across reboots?

I'm currently researching my home router (D-Link 2760-U) which has a (kind-of) proprietary ISP firmware. What I'm trying to achieve is understanding how the router is persisting it's configuration ...
2
votes
0answers
25 views

Why PTRACE_POKEDATA returns I/O error?

I learning usage of ptrace. I tried following simple example but raises a I/O Error. I would like to overwrite "Hello, world" (printing string) from other process. A target program prints &...
2
votes
2answers
103 views

Modern methods of fuzzing/locating heap bugs and potential vulnerabilites

really glad I found this great learning resource. I was wondering, is there any way to fuzz or automate heap vulnerability assesment? I know a lot of practical frameworks for stack based fuzzing in ...
2
votes
0answers
122 views

submitting input into AFL fuzzer

I have some questions about the AFL Fuzzer: How does the AFL Fuzzer know where to inject the payload in the code I compile? For instance if I want to inject it in a specific parameter, how do I do it?...
2
votes
0answers
708 views

Extracting firmware image from binary

I have firmware file in .bin format, but I need get firmware.img image file and Kernel uImage file for reflashing bricked device. How can I get these parts? I used Binwalk to extract content, ...
2
votes
1answer
134 views

What is actually loaded here and different hexdump outputs on util-linux hexdump and on cutter and ghidra's hexdump

I was trying to understand what segment of file gets loaded by fourth LOAD header on phdr array. First 6 headers are shown below from readelf Program Headers: Type Offset ...
2
votes
0answers
681 views

Passing input to program in Remote Debugging with IDA Pro

I am writing an exploit for a binary on Linux using IDA Pro. This binary, first accepts an input using getchar() and after few more code sections, it accepts a buffer as an input through stdin and it ...